• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.2
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• pp.67-78
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• 2000

인터넷의 급속한 발전으로 학교나 기업체 등의 네트워크가 인터넷을 통해 공유되면서 누구에게나 접속이 허용되어 많은 보안상의 문제가 발생하게 되었다 이러한 문제점을 해결하기 위해서 기존의 호스트 기반 보안 정책에서 네트워크 기반의 보안 시스템으로 침입차단 시스템을 설치하지만 침입차단 시스템은 보안을 위하여 최소 권한만을 인정하므로 사용자에게 투명한 서비스를 제공해주지 못한다. 따라서 본 논문에서는 침입차단 시스템에 프록시를 두어서 서비스의 투명성을 제공하고 강력한 보안 기능을 갖는 FTP 프록시 보안모델(FTP-PSM : FTP Proxy Security Model)을 설계 및 구현을 하고 원격 보안 탐색 도구인 SAINT를 이용하여 FTP-PSM의 안전에 대한취약성 여부를 분석하고 보안기능과 성능과의 관계를 응답시간 측정을 통해 측정함으로써 평가하였다 FTP-PSM은 강한 인증 기능을 위하여 일회용패스워드기능을 제공하고 정당한 사용자에게 서비스 제공여부를 결정하기 위해 강제적 접근제어와 임의적 접근제어 기능 그리고 FTP 명령어 사용 권한을 사용자 그룹별로 인증하는 기능을 제공하여 FTP 보안의 문제점을 해결한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.267-282
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• 2000

With the development of computer&network technology and the growth of its dependance, computer failures not only lose human and material resources but also make organization's competition weak as a side-effect of information society. Therefore, people consider computer security as important factor. Intrusion Detection Systems (IDS) detect intrusions and take an appropriate action against them in order to protect a computer from system failure due to illegal intrusion. A variety of methods and models for IDS have been developed until now, but the existing methods or models aren't enough to detect intrusions because of the complexity of computer network the vulnerability of the object system, insufficient understanding for information security and the appearance of new illegal intrusion method. We propose a new IDS model to be suitable at the information system organized by homogeneous hosts and design for the IDS model and implement the prototype of it for feasibility study. The IDS model consist of many distributed unit sensor IDSs at homogeneous hosts and if any of distributed unit sensor IDSs detect anomaly system call among system call sequences generated by a process, the anomaly system call can be dynamically shared with other unit sensor IDSs. This makes the IDS model can effectively detect new intruders about whole information system.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.9
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• pp.315-320
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• 2015

In cloud computing, server virtualization supports one or more virtual machines loaded on multiple operating systems on a single physical host server. Migration of a VM is moving the VM running on a source host to another physical machine called target host. A VM live migration is essential to support task performance optimization, energy efficiency and energy saving, fault tolerance and load balancing. In this paper, we propose open source based adaptive VM live migration technique. For this, we design VM monitoring module to decide VM live migration and open source based full-virtualization hypervisor.

• KIISE Transactions on Computing Practices
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• v.22 no.6
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• pp.278-283
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• 2016

Due to explosive increase in the amount of data produced recently, cloud storage system is required to offer high and stable performance. However, VM (Virtual Machine) migration may result in lowered storage service performance. Especially, in an environment where the host-side flash cache is used in a cloud system, the existing warmed up cache is lost and the problematic cold start begins at a new cache due to a VM migration. In this paper, we first demonstrate and analyze the cold start problem and then propose Cachemior (Cache migrator) which enables efficient hot start of the flash cache.

• Journal of the Korea Society of Computer and Information
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• v.19 no.4
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• pp.81-90
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• 2014

As mobile devices have become widely used and developed, PC based malwares can be moving towards mobile-based units. In particular, mobile Botnet reuses powerful malicious behavior of PC-based Botnet or add new malicious techniques. Different from existing PC-based Botnet detection schemes, mobile Botnet detection schemes are generally host-based. It is because mobile Botnet has various attack vectors and it is difficult to inspect all the attack vector at the same time. In this paper, to overcome limitations of host-based scheme, we compare two network-based schemes which detect mobile Botnet by applying HMM and SVM techniques. Through the verification analysis under real Botnet attacks, we present detection rates and detection properties of two schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1153-1160
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• 2002

So far, the main applications of mobile client are querying data. However, we need a new mechanism to update data at a mobile client as mobile systems are advanced and extended. So, we present a optimistic concurrency control to schedule mobile transactions may include update operations.'rho read-only transactions can be terminated without sending information to a server, and update transactions are terminated by validating at a server. In our method, we can reduce the additional aborts by using a timestamp ordering and serialization graph test mechanism rather than using only conflict information between concurrent transactions.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.9
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• pp.1145-1157
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• 1999

본 논문에서는 RFC 2022에서 제안한 MARS 모델을 기반으로 하여 단일 대규모 클러스터를 가지는 ATM 망에서 다중의 멀티캐스팅 서버(MCS)를 이용한 멀티캐스팅 방안을 제안하고 그 성능을 평가하였다. 클러스터 내의 한 ATM 호스트가 특정 IP 멀티캐스트 그룹에 가입할 경우 ATM 호스트의 위치와 이미 존재하는 멀티캐스팅 서버들 사이의 전송 지연을 고려하여 가능한 한 종단간 전송 지연을 최소화하는 멀티캐스팅 서버를 선택하는 방안을 기술하였다. 이 방안은 최단거리 경로 알고리즘(shortest path algorithm)에 기반하여 최적의 MCS를 선정하고 송수신자 사이의 최소 지연을 가지는 멀티캐스트 트리를 구성한다. 다양한 망 위상에서 MCS의 분포 패턴을 다르게 할 경우에도 이 방안은 멀티캐스트 트리의 평균 전달 지연을 줄이는 것을 시뮬레이션을 통하여 확인하였다.Abstract In this paper, we proposed a scheme to support multiple MCSs over a single and large cluster in ATM networks, evaluated its performance by simulation. When an ATM host requests joining into a specific multicast group, the MARS designate a proper MCS among the multiple MCSs for the group member to minimize the average path delay between the sender and the group members. This scheme constructs a multicast tree through 2-phase partial multicast tree construction based upon the shortest path algorithm.We reduced the average path delay in multicast tree using our scheme under various cluster topologies and MCS distribution scenarios.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7C
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• pp.743-750
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• 2003

With the expansion of computer technology the mobility of a mobile agent code having the flexibility in the dispersive computer situation is used to set up the applications distributed on the Internet. As it also has the ability to transmit the mobile code of a mobile agent and to receive it from a far-off host, the executive circumstances of the host system in which an agent is executed have to access to an agent code and the executive state capable of executing an agent code. Therefore, it is difficult to prevent the forgery, the alteration and the wrong execution of an agent from a malicious host. This dissertation suggests the mechanism which can protect an agent from the malicious action through the executive pursuit of a code-named mobile agent. The security of this mechanism is verified through the protective process of a mobile agent in this mechanism.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.23-29
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• 2004

In this paper, the asynchronous quasi dual-port SRAM employing a single port structure in SRAM embedded SOC (System On Chip) is proposed. External host can access the internal SRAM freely and the data on internal SRAM can be transferred to an another external circuitry without a synchronous signal of an external host, which operates as an asynchronous dual-port SRRAH The performances of the proposed circuits and control structure are verified through the simulation and we fabricated it using a 0.35um CMOS technology. As the results, the chip shows reduced area about 20% and saved power also 20% than conventional architectures.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04a
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• pp.59-62
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• 2002

최근 네트워크 구성이 복잡해짐에 따라 정책기반의 네트워크 관리기술에 대한 필요성이 증가하고 있으며, 특히 네트워크 보안관리를 위한 새로운 패러다임으로 정책기반의 네트워크 관리 기술이 도입되고 있다. 보안정책 서버는 새로운 정책을 입력하거나 기존의 정책을 수정, 삭제하는 기능과 보안정책 결정 요구 발생시 정책결정을 수행하여야 하는데 이를 위해서는 보안정책 실행시스템에서 보내온 경보 메시지에 대한 분석 및 관리가 필요하다. 따라서 이 논문에서는 정책기반 네트워크 보안관리 프레임워크의 구조 중에서 보안정책 서버의 효율적인 보안정책 수림 및 수행을 지원하기 위한 경보데이터 관리기를 설계하고 구현한다. 그리고 경보 데이터 저장과 분석을 위해서 데이터베이스 스키마를 설계하고 저장된 경보데이터를 분석하는 모듈을 구현한다. 또한 불량사용자나 호스트의 관리를 위하여 블랙 리스트 매니져를 구현하며 블랙리스트 매니져는 위험한 불량사용자와 호스트를 탐지하여 관리하는 기능을 제공한다 구현된 경보 관리기나 고수준 분석기는 효율적인 보안정책관리를 지원하게 된다.